Check endless sphere; those that do just build faster bikes, but need to upgrade some parts (wheels, tires, ...). Others build something in the 35 mph class which is inexpensive, easy and doesn't require more robust parts. However, 100 miles @ 20 mph would require (20 - 25 wh/mile X 100 mi = 2,000 - 2,500 wh) or a 52V, 40 -50 ah battery. If you could find space for it, the weight would be 30+ pounds.